This invention relates to methods of making heat exchangers, and, more particularly, to methods of making heat exchangers having outwardly projecting fins spaced longitudinally therealong, and wherein the faces of the fins have roughened surfaces.
It is a primary object of the present invention to afford a novel method of making a heat exchanger.
Another object is to afford a novel method of making a heat exchanger wherein external fins are formed by cutting or gouging the same from wall portions of the heat exchanger.
The making of finned heat exchangers by cutting or gouging the fins from surfaces on tubular members has been heretofore known in the art. For example, the making of spined heat exchangers by cutting or gouging the spines from outwardly projecting ribs on a tubular member has been heretofore known in the art, being shown, for example, in my earlier U.S. Pat. No. 3,202,212, issued Aug. 24, 1965; and in U.S. Pat. Nos. 3,866,286, issued to Stephen F. Pasternak on Feb. 18, 1975; 3,886,639, issued to Stephen F. Pasternak on June 3, 1975; and 3,947,941, issued to Joseph M. O'Connor, on Apr. 6, 1976.
Also, the making of finned heat exchangers wherein spines are formed as integral parts of a larger fin member by cutting or gouging the spines from outwardly projecting ribs and cutting or gouging the remainder of the fin members from material underlying the ribs has been heretofore known in the art, being shown, for example in U.S. Pat. No. 3,692,105, issued to Joseph M. O'Connor, on Sept. 19, 1972, and in my co-pending applications for U. S. Pat., Ser. No. 198,458, filed Oct. 20, 1980, and Ser. No. 204,210, filed Nov. 5, 1980.
It is an important object of the present invention to afford a novel method of forming finned and/or spined heat exchangers.
It is known that in the making of finned and/or spined heat exchangers in accordance with the teachings of all of the aforementioned patents and the aforementioned patent applications, the faces of the fins, facing in the direction of the travel of the cutting tool in the making of the cut, are substantially roughened. Such roughening commonly is in the nature of bubbles having a thickness of 0.001 to 0.002" on fins having an over-all thickness of 0.009". This, in spite of the face that the reverse sides of such fins and the underlying surfaces of the work-piece, from which the fins have been cut or gouged, are shiny smooth in nature. It is my opinion that such roughening of the one side of such fins is caused by the thickening and fore-shortening of the fins during the gouging action--cuts of substantially less thickness (such as 0.003") and of greater length (such as 1.125") being used to produce fins of substantially greater thickness (such as 0.009") and lesser length (such as 0.4").
It has been found that even having the one roughened surface on such fins, as those disclosed in the aforementioned patents, is advantageous in a heat transfer member, affording a greater heat transfer surface area; assisting in breaking up laminar flow past the fins; creating turbulence in the working fluid passing between the fins; and tending to break up the boundary layers of working fluid disposed immediately adjacent to such roughened surfaces.
It is an important object of the present invention to increase such advantageous performances of heat transfer members by increasing the roughening of the cutter-remote sides of such fins in a novel and expeditious manner.
It is another object of the present invention to increase such advantageous performances of heat transfer members by enabling, if desired, both sides of such fins to be roughened in a novel and expeditious manner.
Another object of the present invention is to afford a novel method of making finned and/or spined heat exchangers wherein, at least, the aforementioned increased roughening of the cutter-remote sides of the fins is brought about by perforations being formed in the aforementioned tubular surfaces, just prior to the fins being cut or gouged from such surfaces.
Methods of making heat exchangers wherein openings or indentations were formed in the aforementioned surfaces of heat exchangers, prior to fins and/or spines being cut or gouged from such surfaces have been heretofore known in the art, being shown, for example, in U.S. Pat. No. 3,901,312, issued to Stephen F. Pasternak, on Aug. 26, 1975, and wherein openings, extending through the aforementioned surfaces in a direction longitudinal to such heat exchangers, were formed prior to the cutting or gouging of fins from those surfaces; and U.S. Pat. No. 3,947,941, issued to Joseph M. O'Connor and Stephen F. Pasternak on Apr. 6, 1976, wherein openings or depressions were formed in the ribs of a ribbed heat exchanger by toothed rollers, during the longitudinal feeding of the work-piece prior to the cutting or gouging of the fins and/or spines.
It is an important object of the present invention to afford a novel method of making finned and/or spined heat exchangers, having openings through the fins and/or spines, and which method is distinguished from and patentable over the methods taught by the last mentioned patents.
Another object of the present invention is to afford a novel method of making finned and/or spined heat exchangers of the aforementioned type, wherein the surfaces from which the fins and/or spines are cut or gouged, are formed in a novel and expeditious manner.
An object ancillary to the foregoing is to afford a novel method of the aforementioned type, wherein the forming of the indentations is made as an individual operation with respect to the respective surfaces from which the individual fins are cut or gouged.
A further object of the present invention is to afford a novel method of making finned and/or spined heat exchangers, in the aforementioned manner, wherein the cutter-adjacent sides of the fins and/or spines are roughened in a novel and expeditious manner.
Another object of the present invention is to afford a novel method of the aforementioned type, wherein the roughening of both the cutter-remote side and the cutter-adjacent side of individual fins may be effected in a novel and expeditious manner.
Another object of the present invention is to afford a novel method of making heat exchangers which is effective to afford, in a novel and expeditious manner, increased turbulence in air or other working fluid passing across the completed heat exchanger.
Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what I now consider to be the best modes in which I have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.